It was once thought that there were only two original examples of the Daniel Fahrenheit thermometer in existence - until now, that is.
A third has recently been discovered in a private collection, where it has spent the past 40 years, and will feature as the main draw at Christie's London showroom on October 9.
Dutchman Fahrenheit first invented the mercury thermometer in 1714 and it was thought that only two - both now housed in Boerhaave Museum in the Netherlands - had survived until the present day. It is not certain how many Fahrenheit produced or even when he began making the thermometers commercially, though one of those housed in the Boerhaave Museum is dated 1718.
The example at auction measures just 4.5 inches long and is made of brass. It is thought that it was likely owned by a great scientist of the day, though Christie's has admitted that it isn't sure who that may have been. Signed "Fahrenheit Amst", it is expected to sell in the region of £100,000.
Christie's James Hyslop told the Daily Mail newspaper: "People are very excited by it and we hope that museums might come in and bid for it."
Fahrenheit had previously made barometers with thermometers attached, and invented the alcohol thermometer years before the mercury example; however, it is for the mercury thermometer that he is best known. His invention also led to the creation of the Fahrenheit scale, which is still in use today.
Paul Fraser Collectibles has two superb items from another great inventor - Thomas Edison. We are currently offering an extremely rare example of Edison's stock ticker machine, one of his earliest inventions. We also have a fantastic example of his signature, which graces the annual report of the Edison Spanish Colonial Light Company.